This invention relates to fuel dispensing nozzles, and more particularly to apparatus for limiting the rate of flow of fuel through a fuel dispensing nozzle such that it is prevented from exceeding a preselected maximum flow rate.
Fuel dispensing nozzles are commonly used to dispense gasoline or other fuels into fuel tanks of motorized vehicles. Conventional dispensing nozzles include a nozzle body defining an internal flow passage extending between the nozzle inlet and its outlet. The inlet of the nozzle is connected to a supply hose which feeds pressurized gasoline or other fuel to the nozzle. This pressurized fuel passes through the internal flow passage to an outlet which consists of, or is connected to, a spout which serves as the discharge end of the nozzle. The spout is inserted into the neck of a motorized vehicle's fuel tank during filling operations. The pressurized fuel flow through the internal fuel passage is conventionally controlled by a valve which is actuated by a manually operated valve lever selectively depressed by the nozzle user during dispensing operations.
Fuel, under pressure created by a pump, is fed through the nozzle at flow rates established by the pump capacity and the extent to which the valve lever is actuated. It has been found that the rapid flow rates capable of being generated by conventional fuel pumps feeding the nozzle produce gasoline or other fuel fumes which escape into the atmosphere. Due to the wide spread use of dispensing nozzles and the volume of fumes escaping during dispensing operations, government regulations have been proposed which are designed to limit the rate of flow of fuel through the dispensing nozzle. By limiting the rate of flow, the amount of fumes escaping can be reduced to a level which is less likely to cause significant damage to the earth's atmosphere.
One of the problems in limiting the fuel flow through a fuel nozzle is that the fuel inlet pressure varies considerably at the various dispensing stations, e.g., the fuel inlet pressure may vary between approximately 8 psi and above 55 psi. If a small diameter nozzle outlet were utilized, and if a 10 gallon per minute level were to be established at 55 psi, then at an 8 psi station the flow through the nozzle would be too low from a practical standpoint. If the 10 gallon per minute flow limitation were established at 8 psi, then the flow rate would be excessive at a station pumping at 55 psi. Additionally, fuel dispensing nozzles include manually operable valving so that an operator ca control the amount of flow through the nozzle in a range from a small amount to the maximum amount that the nozzle can dispense. Thus, in limiting the maximum amount permitted to be dispensed through the nozzle the flow limiting device must take into consideration that when the manually controlled valving is only partially open, the flow limiting device should not retard flow until the predetermined maximum amount permitted is attained, and in those cases where the manually operable valving is opened to permit flow greater than that predetermined maximum amount, the flow limiting device should then take over and limit the fuel flowing through the nozzle to the predetermined maximum rate.
In our aforesaid copending application a fuel dispensing nozzle such as those at gasoline service stations and the like proposed a flow restriction device within the body of the nozzle, the device including a flow restricter which is mounted in the nozzle which is automatically operable for restricting the flow through the nozzle to a predetermined amount after the flow rate through the nozzle reaches that predetermined rate. When the rate of flow through the nozzle is less than the predetermined threshold flow rate, the restrictor is automatically operable to eliminate the restriction. The automatic operating means includes a helical blade member operatively associated with respective orifices, the blade member having reactive surfaces for moving a portion of the blade members to a position at least partially blocking the associated orifices to restrict the flow, and in another embodiment the flow restricting means has at least one orifice and includes means which define at least one reactive surface which when acted upon by the flow of fuel serves to slide a member to at least partially block the orifice to restrict the fuel flow. In other words, the flow restricting means is effected by the forces of the flowing fuel upon reactive surfaces causing a pressure differential proportional to the flow rate to move a restricter to partially block an orifice either by a sliding or a rotating action of a restricting device.
Thus, in our aforesaid patent application fuel flow is restricted by reducing the area through which the fuel can flow by means of the forces generated by the flowing fuel acting against reactive surfaces. It therefore requires restricters with sufficient reactive surface area to be established, and the correlation of such areas on elements having nonconventional geometric configurations may be difficult to attain.